I hope your films won't be polluting in the process of biodegrading since as one knows there are many type of biopolymers and biodegradation mechanisms.
Certainly it could be a possibility, alternatively adjust the temperature and decrease it, alternatively utilize ultrasonic welding.
Please, keep me posted with your success.
Kind regards
By the way, since here it is autumn, I don't know whether the weather will be nice today...
Just in case, I am sure that you could notice that, sometimes, I also do it and other ones sometimes but I hope I'd be able to improve and become more cautious if someone would kindly point it out.