That appears to be a mistake. Q class fares are discounted economy fares which are not even eligible for mileage upgrades. The lowest available economy class fare where you have enough freedom to move around (ie. refundable, mileage upgrades, etc) is M.
Here is a list of UA
published fare classes for your future bookings:
A = Discounted Fare First Class.
B = Almost Full Fare Economy with minimal restrictions
C = Full Fare Unrestricted Business Class
D = Discounted Fare Business
E = 1K Special Economy Class Award (inventory available only to 1K pax)
F = Full Fare Unrestricted First Class
G = Travel Industry Economy Class fares
H = Higher level Economy Class usually with few restrictions.
I = Business Class Upgrade class from Economy (Also known as 'NC
K = Seasonal Economy Promotional Fares/Reduced Fare Gov’t contract etc
L = Discount Fare Economy with a lot of restrictions
M = Almost Full Fare Economy with few restrictions
N = Economy Class award ticket
O = Business Class award ticket
P = Premium USA Transcon First Class on 3 classers
Q = Discount Fare Economy often with moderate restrictions
R = First Class AWARD TICKET
S = Real Lowball Economy with lot of restrictions. Not always mile earning
T = Discount Fare Economy often with a lot of restrictions
V = Discount Fare Economy often with a lot of restrictions
W = Discount Fare Economy often with many restrictions
X = First Class UPGRADE AWARD from paid Business
Y = Full Fare unrestricted Economy class
Its better to be on the ground wishing you were in the air than be in the air wishing you were on the ground. Fly safe!