Would you consider this a sign of flirting?

There's this guy at my job & due to our schedules every time I come in he is just about to leave & vice versa. So, our interactions usually consist of "Hi" & "Bye". He always greets me with this big smile & even though, he smiles at everyone, I feel like it's a bit different when he smiles at me. I feel like his face lights up with a smile when he sees me (I could be wrong). We have had conversations a couple of times before but they have been very brief. The other day, I was scheduled to use the room that he was in after he left & when I walked into the room, I noticed that there was a jacket on one of the chairs. I called him over to ask him if that was his jacket & he said "Yeah. Why? Do you want it?" with a smile. I just smiled back & told him "No thanks" cuz I was already warm enough with the sweatshirt that I had on. I kind of felt like he was flirting but wasn't sure so I texted my best friend (who doesn't work with me) & she said that he was just being nice. What do you think?