Bord Gais Collections Warning Letter

I have recently closed my account with Bord Gais and received my final bill in July. I was under the impression that it would be paid automatically as that was how all my previous bills had been paid. Turns out that wasn’t the case because I have received a collections warning. I have been away since 2 August, and their letter was dated 27 July (they seem to allow 5 days to pay this) but I obviously didn’t meet this because the letter arrived after that date. I come this evening and immediately pay the bill upon reading the letter. I’m not paranoid that the debt collectors have been contacted. I have emailed Bord Gais about this, confirming that the bill has been paid, etc… Just wondering if anyone else has any experience like this?