Is my dog okay, he has strange breathing habits randomly at night time?

Hi, my dog randomly starts breathing strangely. At night, his breathing is more rapid then usual, however sometimes not very loud, occasionally, and he gets restless. This has happened twice and I took him out to have some water and let him out to get some fresh air, but I don't know. He is a Shitzu x Maltese and is 10years old. Please help me!