I have not had any issues with mine but the thing smells like food and may have grease film in the catcher and that smells like food. Mice will eat little crumbs and lick whatever is on the grill. The hard cover won't keep them out since they can just shimmy in anywhere. It's not ideal but I don't consider it a problem. I just make sure I scrape my grill while it's hot and get all of the particles off that I can. When I use it next time I get it scorching hot before cooking on it.
I think the silicone thing would be good as it would keep your surface clean even if something gets in. Otherwise, I have chickens that jump on the grill and drink the grease out of the catch can. This keeps grease out of the can which reduces other animals from being interested but then you have a chicken problem.
Houston-BCS-Austin-Dallas-San Antonio - Infinity Roofing - https://linqapp.com/jason_duke --- JasonDuke@InfinityRoofer.com --- https://infinityrooferjason.blogspot.com/