Cat had yearly check up yesterday, she's put on a bit of weight which she has before & we got it down without much difficulty, not too worried about that. Vet said she could hear a really faint murmur on one side of her heart, she didn't seem too worried, said that it possibly hadn't been picked up before & could be due to being stressed/weight gain, & that she'd check again in about 6 weeks at a weight check. She didn't seem concerned & I was just a bit surprised so didn't ask about it, googling seems to suggest it's not a huge problem? She's 8, indoors mostly & perfect health otherwise.