Newbie etiquette question

My son and I have been hooked on wakeboarding since late last summer, and get out every weekend. Still definitely "newbies" but we try hard.

So a couple weekends ago, we are out early, hauling to our favorite location on a medium size lake. I look behind and a guy is overtaking us a high speed, waving arms frantically to get us to stop. So I stopped, thinking there was a problem. No. He asks - "Where do you board on this lake that is protected from all this wind?". I reply, "follow me" and take him to the beginning of a long (several mile) stretch of lake that has several good spots. I tell him this, wish him well, then head off - as we pass a spot that looks good (a fairly small area), we turn in - and he follows. Not wanting to be an a-hole, I held my tongue - but it pissed me off, 'cause there is no way the water stays calm with two boats in this small area, and I just told him about several miles of equally good water to explore and find his "own" spot.

Am I being selfish?