Door not latching properly

[Tizercat]

I have a 2016 jayflight 267 BHSW that I purchased used in October 2018. When I got it the door latched easily but over time the door has gotten harder to close and now I have to lean most of my weight on the door to make sure it’s closed it I’m inside or push hard from the outside. I always lock the door to make sure it’s closed, but today I left for a few hours after locking (and checking it was closed by tugging on the door from outside) only to return to find the door open (still locked) and nothing missing. Luckily that included my cat! She greeted me at the open door as I ran up to it thinking the worst. Any advice on adjusting the door/latch so I don’t have to undergo that panic again? The unit has gone through a winter since I bought it but I’m in coastal BC Canada so the temperature was not lower than -2C at worst and it’s now under at most 30C if temperature could be an issue, and it is not improved with increase in temperature since I first noticed the issue in Feb or March. Screen latches easily if that is important.

[JFlightRisk]

If it's just the latch binding, lubricate it with either graphite, or silicone spray, and a swipe of lube on the striker plate.
If the door is binding in the frame, I'm not sure there's any adjustment to it. If the door is in fact sticking in the frame, there should be a tell-tale mark where it's too close. Again, some lubricant on that area will help, and you'll need to re-lube from time to time.