The primary reason why nasal passages sometimes dry out from CPAP use is lack of adequate humidification.
CPAP air is an irritant – one degree or another – to everyone. The irritation may cause the nasal passages to dry out and bleed, or the mucous membranes may try to protect the nasal passages by producing excess mucous and so congestion results. And the irritation can be cumulative; the problem may develop over time. Furthermore, dry, cracked or bleeding nasal passages are a breeding ground for infection.
Increase your humidity level to add moisture to the CPAP air and reduce or eliminate the irritation. If that produces condensation in the six foot hose, you should try a insulated cover for your hose or a heated tubing.