Im concerned for my snail's health

[Bogs]

I was observing my snail, Toast, (Cornu Aspersum) in their tank last night when I noticed something strange. A bulge in their head like a bubble. I continued observing, preparing myself for their head to burst, but I heard a wet little sound and the bubble deflated, and Toast continued their evening as if nothing happened.
Furthermore, I looked back at old pictures and noticed the bulge was present in multiple old photos dating back to September, but I believe they may have been living with this for longer.

Which brings me to my question: is this normal/safe? if they've been living with it for this long and seem fine... does anybody know what this is? something natural or a disease? Are they in pain? 

Any answers would be greatly, greatly appreciated. thank you

[Rasplutin]

Possibly your snail needs a partner.
Did the bubbles look like the ones shown here:

petsnails.proboards.com/thread/17448/aspersa-frisky

?

[Bogs]

No, i added a picture to my post. just a massive bulge in their forehead. But i did a little research and it seems to be a "head Wart" which is swelling of a genital gland and is just a sign of sexual maturing in snails. So all is well i think