Yes, it's normal. You tend to go up in 2,000ft increments. However, winds change aloft and sometimes your flight plan may well ask you to drop down 2,000ft to take advantage of a jetstream for example. All I know is always looking to go higher works mostly, but it does pay to look at the upper winds first. Sometimes you are given lower levels to avoid slots and restrictions on a part of the route, which in reality are not needed. other times it's for weather and helps a lot. Just being aware and paying attention can make the difference. Not that managers will ever credit you for doing it..