Python Nerds Gather Round

I have a Raspberry Pi monitoring my old oil boiler for when it's actually running/burning from this I can calculate oil use.

Old System
Python script that 'listened' to the volume of the surroundings using a USB microphone.  Above a certain level the burner was running, below the level it was not.

Problem was that there were some errors due to outside noise and the Pi being in a steel box was not good for wifi signal.

New System
I've a relay triggered by the 28v power supply to the oil pump solenoid (only on when the burner is running) - the other side of the relay closes a connection on one of the Pi GPIO pins - works great.  The script checks the state of the pin every 5 seconds.

The little issue I'd like to fix is this:
A few seconds before the pump solenoid opens, the boiler controller send a quick burst (less than 1 second) of 28v to the solenoid and then it drops back to 0v before it fires properly a few seconds later.   This quick burst is enough to trigger the script which shows as the boiler being on for 5 seconds then going off again, before starting properly.
It's not a major issue as my app filters out burns of less than 1 minute - but it's just not 'tidy' and does create 4 webhook messages to IFTTT rather than just two for each burn.

I thought I could get the script to wait a couple of seconds and then re-check the pin status before deciding that the burner was on.... but it's not working and still records the first power blip.

This is the code that does the checking - have I got this wrong?

boiler_status = 0

while True:
input_state = GPIO.input(13)
if input_state == False and boiler_status == 0:
print("Waiting")
time.sleep(1)      # wait to see if the pin condition stays the same
if input_state == False and boiler_status == 0:       # if it is then the boiler is running
print('Boiler On')
boiler_status = 1
time.sleep(5)
r = requests.post('https://maker.ifttt.com/trigger/Boiler_On/with/key/blahblah',params={"value1":datetime.now()})

elif input_state == True and boiler_status == 1:
boiler_status = 0
print("Boiler Off")
time.sleep(5)
r = requests.post('https://maker.ifttt.com/trigger/Boiler_Off/with/key/blahblah',params={"value1":datetime.now()})

This is what I get in my spreadsheet for a single burn:
February 18, 2023 at 03:12PM Boiler_On 2/18/2023 15:12:35   <------ Power blip
February 18, 2023 at 03:12PM Boiler_Off 2/18/2023 15:12:40
February 18, 2023 at 03:12PM Boiler_On 2/18/2023 15:12:47   <------ Actual burn start
February 18, 2023 at 03:21PM Boiler_Off 2/18/2023 15:21:24