Bubble nests rare?

[bloo97]

Lucky has a HUGE bubblenest. I felt bad when i put his leaf in and accedentally destroyed it. ) :

[smallvle]

now i don't feel so bad! my old fish Phin, (now this was when i knew bettas should not be kept in an un-heated cup, but not much more,) was in a 1 gal, heated bowl with weekly water changes, (i know better now!) and always had a bubble nest! but now my guy Seuss who is in a filtered/ heated 2.5 gal tank has only made a couple of nests in the year i've owned him. but i think he's older, so i just figured he was past breeding. i've always associated bubble nests with happiness, but Seuss seems very happy. i feel better knowing not every betta makes them all the time though. : )