Feeling Left Out of My Bestie's Concert Plans

my bestie is going to a concert for a band i REALLY like. I'm super excited for him! it's just... i mentioned before they started making new music like "id love to see them if they ever come back and do more music". i guess he and another of his pals said a similar thing, saying something more specific almost? like "oh if they ever come back we have to go see them". so my bestie and that other friend are going to see the band. at one point my bestie even invited his gf and her best friend to go with. i just feel kinda upset about it. i know my feelings are valid but i also feel like an asshole for feeling this way :( i want them to have a good time, i truly do! i just feel... idk. left out? maybe? idk. I can't pinpoint it exactly :// anyways, would this kinda fall under rsd (rejection sensitive dysphoria)??