What could cause a low-pressure compressor first stage blade of a turbofan engine to bend forward?
Forward bending of the first stage of the low pressure compressor is usually associated with (soft) Foreign Object Damage (FOD). 

Ice and/or large quantities of snow in the engine intake will typically cause forward bending of the leading edge of the tip of the blades. 


 Damage to GE CF680C2 turbine engine compressor fan blades after snow/ice ingestion 
Source: Flight Safety Australia


 Damage to Turbomeca gas turbine Arriel 2B turbine engine compressor blades after snow/ice ingestion  
Source: Transport Safety Board of Canada, aviation accident investigation report A12P0008