Melbourne

Might be. Might also be too dry in parts. I would cut it back severely, aerate the soil around the plant (fork lift method) and apply a slow release fertilizer around the drip zone. Rosemary likes a well drained soil, but does need water and feeding for strong growth. Also, is it in full sun? Rosemary can get sunburned if the sun is too intense. Keeping it bushy rather than letting it go leggy helps a lot to prevent sunburn. Melbourne's rainfall is usually enough to keep an established plant going, but a young plant may need a good soak after a few very hot dry days. I see you've got the mulch sorted, which is good. The reason for the extra fertilizer is to correct any imbalance caused by the mulch decaying and absorbing nutrients that can rob the plant underneath of its nutrition. Pine bark mulch is notorious for this - you usually have to add at least a lime sprinkle under pine bark mulch when it's first laid down. Slow release is better though.