Post Interview question

Hey all,

Just got a question and would like some advice please. I had an interview last Tuesday and it went really well i think. They also said that my resume was really impressive and my experience was a good fit for the role.

After interview i was told latest id hear back was the end of day Friday (today), but havent heard anything since. Im planning to follow up with them Monday, but im just wondering is this a bad sign? Ive not had much experience with interviews so not sure if theyre just busy TIA!