“Tantrums”

At what age is a tantrum actually considered a “tantrum”? My baby is 4 months old, I was eating so my dad was holding her she started crying not crazy but getting fussy and just crying so he’s like “oh these tantrum if you don’t do something about it she’s gonna be bad when she’s older” exactly what am I supposed to do? SHES 4 MONTHS. This is the 2nd person that tells me that. I don’t consider them tantrums whatsoever but you guys tell me. Thank you