Rly confused about this guy, a little help?

okay, this one guy in my cl i've known since, like, 3rd grade, but as we got older it kinda changed but we were still rly good friends. As we got older, he got a lotta girlfriends and flirts with almost everyone, but he'll pick a different girl to focus on for different periods of time. lately he's rly been flirting with me, but longer than he ussually does with anybody, a lot longer. and a little more serious flirting Should i take i seriously, or just as a bit of a stretch?