yah that has happened to me before either that or i land to hard and collapse the front nose wheel
I seem to recall reading somewhere that the front wheel was a bit of a problem with the 39's, the strut wasn't really up to repeated landings on rough front line fields and a collapse nose gear wasn't uncommon. I'll flip through some of the books on the 'ol shelf and see if I can find a quote.
If you like flying the P-39 I heavily recommend reading "Nanette" by Edwards Park who flew P-39's (I think his was an N model)with the 41st Fighter Squadron, 35th Fighter Group in New Guinea. It's practically required reading in the 80th here these days.
Can be found online at Abebook.com for as little as $3-$5.