Blue lips

My family and I spent the weekend at a hotel.  When I took my 8 year old son to the pool, I noticed he had blue lips.  But we just came out of a party that served cake with blue icing, I thought that was it.  But we returned to the pool later that evening and his lips went blue again.  I had my 6 and 7 year old with us and we were okay swimming.

I asked if he had trouble breathing or chest pains and he said no.  As we settled in our room for the night, he began complaining that his cheeks burned.  The were reddish and I placed a cool wet cloth on his cheeks.  The next morning he was fine.  Again, we went to the pool and again he had blue lips within the first 10 minutes.  

I've never seen this when we'd go swimming whether at this hotel pool or the local pool.  He is in good health.  A fussy eater.  The nearest pediatrician is a 3 hour drive.  Am I worried about nothing?