2.4 twin cam blow by????

[muff34]

Hi guys
Just looking foor some answers about a Grand Am I looked at tonight. `01 GA 2.4 twin cam with approx 70,000 miles on it . nice car however I popped the oil filer cap off it while it was running to check for any "blow by" and the air that was coming out of it was unreal. No smoke just lots of pressure. When I bought my Silvy with the 4.3 in it a Diesel mechanic I know told me to check for this "blow by" . 145,000 miles on it and nothing blowing out that oil filler hole . my truck runs like a charm and was just wondering about this car . Salesman said nothing to worry about unless it`s blue smoke. My chum told me before blow by could be from bad valve seals . Any comments people ?
Thanks Muff