Is this a red flag?

I met a guy through Instagram, he messaged me and said he was interested in getting to know me and we hung out for the first time yesterday. We talked over text for a while and things were going beyond great so I invited him over to cook and spend the night. We met at the grocery store so we could get food ingredients together (and meet in public for the first time) but the minute I saw him I got instant bad vibes. I honestly still don’t know why, maybe because I’m 21 and he’s 26 and looks pretty old but I was so uncomfortable that once we got back to my place I ended up asking him to leave. He begged me to take things slower and to give him a chance but he was weirdly emotional about it and said he just felt “drawn to me” and that he felt like this could work. Is he just a nice guy interested in me or should I trust my instincts and run??