Callistemon leaves going red?

We inherited a large callistemon - not sure of the variety but it's about to start flowering with gorgeous pink brushes.

However, the last couple of weeks I've noticed some of its leaves turning red - is this normal or should I start worrying?

The picture is upside down (couldn't figure out how to get it right way up) but you can see that there are flower buds in the middle of image but some of the foliage further down the stem has gone bright red. Please tell me it's not dying?