It is normal development.
The people who grow them commercially are clever to make sure plants look perfect when they are offered for sale and we often forget that plants keep growing, will out grow their space too.
Potting up into larger pots at regular intervals or actively dividing and separating plants can make 'house plant gardening' a bit of fun too.
The stems of flowers can be cut back to the base and the excesses should transplant into smaller pots.
I know the instinct is fear of killing the original plant, but you can not reverse time and get them back to what they were.