I've been battling air lines coming off, a lot lately... I bought what I thought was good silicone tube... as
@Uberhoust suggested, I got some black line, recently, as I thought it wouldn't stand out as much in my tanks, & that has not popped off yet... ( but it's only been in use on one line for a little over a month )
I may be in a minority here, but I throw away check valves ( well actually my air line hardware box is full of them ) they add resistance to your air line, & a long time ago, when I did use them I had one fail... IMO, any mechanical safety is prone to fail, whether you are talking gun safeties, or aquarium check valves... the best safety is between your ears... I only mount my air pumps higher than the glass ( you can put the air pump on the cover to the tank, as long as it's above the water line ) & I'm sure there are covers that putting the air pump on it would be inconvenient, but there are times, that the power could go out, & the line could syphon water out through your air pump, & wreck your air pump in doing so, & or short circuit your outlet, with a wet air pump...
fortunately the lines are small, & typically don't go to the lowest point in the tank, so if you didn't catch it, the syphon usually breaks, before the tank is drained dry. the fish usually survive, & I'm glad your fish made it... how big a tank was it???