baby waking with a sudden "whoop" or inrush of breath - apnea??

[babydriver]

Hi, DS2 sometimes wakes from the middle of his sleep with a big whooping type noise, which sounds like he's gasping for a big breath. Typically, it's in the middle of the night or his long daytime sleep and I'm woken/alerted by the noise but not seen what preceded it. Could it be a symptom of apnea or am I being paranoid?

He's 4mo and has been doing this for a week or so. Also seems to be teething, having a bit of a cough, possibly some reflux (symptoms all similar!).