Is it normal for a trampoline to squeak?
If the squeaking is not very loud, the cause may be the first stages of rusting on the trampoline spring. This is the case especially if the product was stored in a wet place for a long duration and it was not being used.
Let the trampoline dry in a dry environment. Once it has dried, apply some WD40 on the metal joints and springs. Finish by applying trampoline grease in these areas.