Does my thunbergia alata have some sort of disease?

Hi everyone, sorry for spamming these forums with questions these last few months - I've been growing thunbergia alata from seed since November. I think they're doing pretty well, but one plant has these nasty red pustules on some of the leaves. I pulled them off and have photos below - does anyone know what this is/what it means/what I need to do? I've got a photo of the rest of the plants for context. Thanks