So I've let my sis use my sons infant carseat since her daughter was born, she's 1 year and 2 months…

So I've let my sis use my sons infant carseat since her daughter was born, she's 1 year and 2 months old now, would it be rude to ask for the carseat back tomorrow before they move away??? Like she has another infant carseat for her that's in my moms van and my sis has also several toddler seats and she won't be in the baby one much longer but I don't want her to take the carseat for years to come and it get damaged or dirtied up. Or even molded when she eventually stores it in a storage building when she outgrows it. Not saying ima have any babies any time soon but that's my sons first carseat I actually saved up and bought before he was born I got it with the matching stroller and whenever I plan to have another they will use it if it's not expired by then that is lol. I just don't know how to ask about it without sounding rude or greedy. Cause she does and has let me borrow all her sons clothes jackets shoes for my son since he was born. She's helped me so much and I'm thankful so I do the same for my niece. But like I said I don't want it dirtied up or my nephew drawing on it or anything like that...